In the fiber optics communication industry, many companies have developed means by which optical fibers can be connected to one another. Splicers, in particular, come in two primary forms: fusion splicers and mechanical splicers. A fusion splicer physically fuses the ends of two optical fibers together by the application of heat, typically from an electrical arc. Fusion splicers are advantageous in that they create splices in which the insertion and return losses are precisely controlled. However, fusion splicing is complicated, expensive and requires advanced technical equipment not readily suited for use in the field, particularly if the local electric power required is not available.
A mechanical splicer is a junction of two fibers aligned with one another and held in place within a ferrule or similar assembly. The fibers are not physically joined as in a fusion splice. Rather, the fibers ends are held very close together with the optical index matching gel in between within the ferrule so that light can pass from one end to the other end with least amount of disturbance. Mechanical splicing is preferred for use in the field because of its ease in application and simplicity in terms of labor, training and equipment cost. However, mechanical splicing techniques developed to date have not been able to control insertion and return losses within prescribed limits required by many areas of the communications industry, thus as the max insertion loss below 0.3 dB, and max allowed return loss below −60˜65 dB for SC/APC connectors.
Mechanical splicers for optical fibers have been used conventionally for about the last twenty years. During that period, various technology has been developed in the prior art to improve existing mechanical splicers. The improvements have focused on methods and devices for better aligning the ends of the fibers connected by the splicer. Alignment has been only slightly improved as a result of these efforts. Also, through improvements in the nature of the fiber manufacturer, the eccentricity, also referred to as concentricity, of the fibers has been improved, which in turn has resulted in better alignment of fiber ends during mechanical splicing. In addition, index matching gels (sometimes referred to as “JELs”) have been developed in the prior art. Such gels are typically placed within the mechanical splicer to fill any slight gap, usually in the micrometer and nanometer range, between the fiber ends. Index matching gels provide a smooth continuity for light to pass through the gap and consequently control insertion and return losses. The prior art has improved the chemical stability of existing gels so that they can withstand drying, crystallizing and discoloring when subjected to temperature variations and aging. In particular, improvements have been made to ensure that the gels do not crystallize at low temperatures, do not evaporate at high temperatures, do not change colors during the course of its life time, and do not change the optical index too much under different environments. Designing such gels to achieve these improvements is complex and requires many technical manipulations. With all the proper investment, the optical matching gel issues have been resolved for the most part.
With advancements like those discussed above, the prior art has developed optical fiber mechanical splicers for use in the datacom grade. But the prior art has to date not been able to develop mechanical splicers for use in the telecom grade. In the telecom grade (such as the requirements provided by GR-20, GR-326), the connector itself is terminated in such a way that makes splicing easy, but the return loss specification was never very low enough (−64˜65 dB). The problem with return loss is caused by the use of a flat cleaver to cut the fibers. With a flat cleaver, the cutting surface of the cleaver is perpendicular to the transmission axis of the fiber. Using a flat cleaver, the prior art methods could create a mechanical splice with a relatively controlled insertion loss, but the return toss (about −40 dB) was not controlled and not lowered enough due to the nature of the physical interfaces. In telecom communications, especially in the video grade, the industry requires a high ranking specification for return loss of greater than 60-65 dB in absolute value, or lower than −60˜65 dB. The prior art methods using flat cleavers have been unable to create mechanical splicers that meet this requirement.
The prior art has previously used angled cleavers in developing connectors for optical fibers, such as angled physical contact (“APC”) connectors. The APC connector is typically an 8° polished connector and is manufactured by several companies. In such a connector, the fiber is stripped, cleaved, cleaned and inserted into the ferrule with epoxy, then the connector is cured and endface is polished. The industry, however, still has not developed an efficient way to mechanically splice together two fibers that have been angle-cleaved, wherein the orientation/key is well aligned, and the two end-faces are well compromised for the required optical specifications. In particular, the industry has not developed an effective way of aligning angle-cleaved fibers in the creation of a mechanical splice to optimize insertion loss and return loss. Fibers are typically 125 μm in diameter. When two fibers are cleaved at 8°, it becomes very difficult to align the ends together such that the surface of contact is at an optimum (and the insertion loss and return loss are optimized). The prior art devices and methods have never been able to control this alignment in order to achieve the required optical specifications. Most manufactures simply slide the fiber ends together within a ferrule and are unable to control the surface contact. This leads to a very wide statistical variation in insertion loss and return loss values. Therefore, the true reliability is compromised.